better iteration style for get values

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: vaster
 Title: Tools for Raster Grid Logic 
-Version: 0.0.2.9001
+Version: 0.0.2.9002
 Authors@R: c(person("Michael", "Sumner", email = "[email protected]", role = c("aut", "cre"), comment = c(ORCID = "0000-0002-2471-7511")))
 Description: Provides raster grid logic, the grid operations that don't require access to materialized data, i.e. most of them. 
  Grids are arrays with dimension and extent, and many operations are functions of just the dimension 'nrows', 'ncols' or 

src/coordinates.c

@@ -8,13 +8,19 @@ SEXP bin_from_float(SEXP bins, SEXP range, SEXP coord) {
   SEXP out;
   out = PROTECT(Rf_allocVector(REALSXP, nn));
 
+  // save the index, as per https://github.com/hadley/r-internals/blob/master/vectors.md#get-and-set-values
+  double* rout = REAL(out);
+  double* rcoord = REAL(coord);
+  double cmax = REAL(range)[1];
+  double cmin = REAL(range)[0];
+  double rbin = INTEGER(bins)[0];
   for (int i = 0; i < nn; i++) {
-    if (REAL(coord)[i] == REAL(range)[1]) {
-      REAL(out)[i] = INTEGER(bins)[0] - 1;
-    } else if ((REAL(coord)[i] > REAL(range)[1]) | (REAL(coord)[i] < REAL(range)[0])) {
-      REAL(out)[i] = R_NaReal;
+    if (rcoord[i] == cmax) {
+      rout[i] = rbin - 1;
+    } else if ((rcoord[i] > cmax) | (rcoord[i] < cmin)) {
+      rout[i] = R_NaReal;
     } else {
-      REAL(out)[i] =    trunc((REAL(range)[1] - REAL(coord)[i])/scl);
+      rout[i] =    trunc((cmax - rcoord[i])/scl);
     }
   }
   UNPROTECT(1);